Lesions of the posterior paraventricular thalamic nucleus (PVTp) have been reported to abolish the habituation of HPA secretory responses normally seen upon repeated exposure to an emotional stressor (restraint), without affecting acute stress responses (J. Neuroendocrinol. 14:403-10, 2002). In attempting to clarify the CNS underpinnings of this phenomenon, we made the ostensibly conflicting observation that PVTp lesions reduced activational responses, evidenced by decreased Fos induction, in paraventricular hypothalamic nucleus (PVH) neurons comprising the central limb of the HPA axis in acutely, but not repeatedly, restrained rats (SFN Program No. 506.19, 2003). We sought to reconcile these discrepant findings by evaluating hormonal and PVH activational profiles in a single experiment. Adult male rats, with and without lesions of the PVTp, were subjected to single (acute) or 14 consecutive daily (repeated) 30 min restraint sessions. Serial blood samples were drawn via indwelling jugular catheters, before...